Important Basic Electrical MCQs
In this post, some of the important Basic Electrical mcqs are given. It includes potential of earth, definition of potential, direction of current, unit of current, definition of resistance, definition of power, unit of resistivity, effect of temperature on resistance and reciprocal of resistance.
Basic Electrical MCQs 21 to 35
21 The potential of the earth is
( a )– 10 Volt
( b )10.0 Volt
( c )2.0 Volt
( d )Zero Volt
Correct Answer ( d ): Zero Volt
The earth’s potential remains constant and it is equal to zero.
22 The difference in potential of two charged bodies is called as
( a )Electrical potential
( b )Potential difference
( c )Energy
( d )Charge
Correct Answer ( b ): Potential difference
23 If the two charged bodies have same potential, the potential difference between two bodies is equal to
( a )Zero volt
( b )+ 5 Volt
( c )– 5 Volt
( d )230 volt
Correct Answer ( a ): Zero volt
The potential of charged body A is 25.0 V and that of B is 20.0 V, therefore we can say that potential of A is higher than that of B. The direction of current flows from A to B. if two charged body have same potential, current is equal to zero.
24 The electric current flows due to
( a )Electrical potential
( b )Volt
( c )Potential difference
( d )Energy source
Correct Answer ( c ): Potential difference
25 The potential of charged body A is +25.0 volt and that of body B is +20 volt. The direction of current from
( a )Body A to B
( b )Body B to A
( c )Either ( a ) or ( b )
( d )Both ( a ) and ( b )
Correct Answer ( a ): Body A to B
Basic Electrical MCQs 26 to 30
26 The unit of current is
( a )Coulomb / second
( b )Joule / second
( c )Watt / second
( d )Voltage
Correct Answer ( a ): Coulomb / second
I = Q/t = Coulomb / second
27 How many electrons per second flow through a conductor for one ampere current?
( a )6.25 x 1018
( b )1.6 x 10 –19
( c )1.89 x 1018
( d )2.34 x 1018
Correct Answer ( a ): 6.25 x 1018
Charge of electron is 1.6 x 10-19
for one ampere current, electrons per second = 1 / 1.6 x 10-19
= 6.25 x 1018
28 A battery has emf of 24 volts, it means that it supplies _____ joules of energy to each coulomb of charge.
( a )Zero
( b )Twelve
( c )Twenty-four
( d )None of the above
Correct Answer ( c ): Twenty-four
Emf V = Wq
Where V = Voltage, W = Work done per charge and q = charge
V= 24 Voltage and q = 1 coulomb
W = V/q = 24/1 = 24
29 The rate of change of energy is known as__________.
( a )Voltage
( b )Current
( c )Power
( d )kWh
Correct Answer ( c ): Power
P = W / t
Power = Energy / second
Basic Electrical MCQs 31 to 35
30 The property of material which opposes the flow of current is known as
( a )Conductance
( b )Resistance
( c )Resistivity
( d )Reluctance
Correct Answer ( b ): Resistance
31 Acid and salt solutions are example of
( a )Insulator
( b )Semiconductor
( c )Conductor
( d )Both ( b ) and ( c )
Correct Answer ( c ): Conductor
32 The unit of resistance is
( a )Ohm
( b )Mho
( c )Siemens
( d )Ohm – meter
Correct Answer ( a ): Ohm
33 One tera ohm is equal to
( a )106 Ω
( b )109 Ω
( c )1012 Ω
( d )10 – 12 Ω
Correct Answer ( c ): 1012 Ω
34 The resistance of a metallic conductor is directly proportional to
( a )Area
( b )Length
( c )1 / Area
( d )Both ( b ) and ( c )
Correct Answer ( d ): Both ( b ) and ( c )
Resistance R = ρL/a
Where R = Resistance,
ρ = Resistivity of material,
a = Area of conductor
L = Length of conductor
Therefore, R α L and R α 1/a because resistivity is constant for any material
35 The unit of resistivity is
( a )Ohm
( b )Ohm / m
( c )Ohm – meter
( d )Mho
Correct Answer ( c ): Ohm – meter
Basic Electrical MCQs 36 to 40
36 As the temperature increases, the resistance of the insulator
( a )Increases
( b )Decreases
( c )Does not affect
( d )Any of the above
Correct Answer ( b ): Decreases
As the temperature increases, the resistance of electrolytes, insulators decrease, therefore it has negative temperature co-efficient of resistance.
37 As the temperature increases, the resistance of the conductor
( a )Increases
( b )Decreases
( c )Does not affect
( d )Any of the above
Correct Answer ( a ): Increases
As the temperature increases, the resistance of metal increases. The temperature – resistance graph is straight line. The metals have positive temperature co-efficient of resistance.
38 The resistance offered by a conductor having length of meter and area of one meter square is known as
( a )Resistance
( b )Conductance
( c )Resistivity
( d )Conductivity
Correct Answer ( c ): Resistivity
Resistance R = ρL/a
a = 1 meter square and L = 1 meter
R = ρ(1)/(1)
Therefore R = ρ
So we can say that resistance is equal to resistivity when length is 1 meter and area is equal to 1 meter square.
39 Which of the following has least resistivity?
( a )Gold
( b )Nickel
( c )Silver
( d )Annealed copper
Correct Answer ( d ): Annealed copper
Detail About Annealed Copper
40 The reciprocal of resistance is known as
( a )Conductance
( b )Conductivity
( c )Resistivity
( d )Permeability
Correct Answer ( a ): Conductance
Conductance = 1 / Resistance
Basic Electrical MCQ PDF
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